docs: debugging-via-ohci1394.txt: add it to the core-api book

There is an special chapter inside the core-api book about
some debug infrastructure like tracepoints and debug objects.

It sounded to me that this is the best place to add a chapter
explaining how to use a FireWire controller to do remote
kernel debugging, as explained on this document.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/9b489d36d08ad89d3ad5aefef1f52a0715b29716.1588345503.git.mchehab+huawei@kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
diff --git a/Documentation/core-api/index.rst b/Documentation/core-api/index.rst
index c00aef8..2cfd07a 100644
--- a/Documentation/core-api/index.rst
+++ b/Documentation/core-api/index.rst
@@ -98,6 +98,7 @@
 
    debug-objects
    tracepoint
+   debugging-via-ohci1394
 
 Everything else
 ===============